pregnant or dry up line

Last August I took 2 tests, one of which had a very faint second line. I thought, okay, it's an evaporation line. But now, 4 months later, I'm still on the pill, but my periods are very irregular (less bleeding, one day yes, then a few days nothing, then a little bit again. Every month it gets less and less). Before August, I had normal periods. Now I'm 2-3 days late and I told my mom that I had taken tests earlier. She said she finds the second line very faint and doesn't trust it. Now we're secretly hoping I'll get my period anyway... I'm only 21 and I find it quite scary. I was wondering if you think it's an evaporation line or if I should take another test. I hope you can help me a bit!